Adolescent Body Misperception

This study provides novel evidence on the role of social comparisons in shaping adolescent body misperception. Using an instrumental variables approach leveraging variation in relative age generated by school entry cutoff months and data from the Health Behaviour in School-Aged Children study, the study shows that relatively older students are more likely to misperceive their weight harshly relative to their BMIs compared to their same-age counterparts who are relatively younger within their classrooms. Meanwhile, relatively younger students are more likely to misperceive their weight leniently relative to their BMIs. 

Relatively older students are less likely to be overweight or obese, consume more low-calorie foods, and report higher levels of physical activity. 

Overall, the results suggest that relatively older students base their weight-related expectations and behaviors on their younger peers, while relatively younger students compare themselves to their older peers.